I think everyone know the history of Sai, he comes from ANBU, as usual, the strength of ANBU amount to one Jonin. And during the exercise among Yamato captain, Naruto and Sai, Sai subdue Yamato alone, on the other hand, Sai is under the leadership of Shimura Danzou who have ability to snatch the 3rd Hokage, so Sai’s strength is cannot be taken lightly.

9th —- Karin

In our eyes, Karin is one intellectuality Ninja, his ability is to perceive chakra and the count of people within a certain range. The strength of her we know is too little. Orochimaru is one S Ninja who pursue all kinds of Ninjutsu and Eternal Life. He select Karin might not only for these strength.

8th — Moon Water

Moon Water would melt his body into water, he is the Synthesis of water, in the early episodes, Moon Water seems just like a brute force Ninja. And later, he said he is the little brother of Hohzuki Mangetsu and the young master of Zabuza, just from these, his suiton is assignable, and few people dare to challenge Hoshigaki Kisame except him.

7th— Jugo

Jugo is Two-way personality, his ability is to control curse seal to change his body become a powerful weapon to attack others, and it also turn intoa shield to defend. His strength we do not know very well, but the orochimaru could not defeat him; his strength must very strong.

6th — Tsunade

I think everyone could recognize her strength, her ability is the super brute force and medical Ninjutsu, besides, and she also has an Eternal Life.

5th— Konan

Konan have some strange, her could said be a unbeatable detective, and she can also turn into the paper to investigate or attack others. Even so, I think her ability is not just these.

4th — Pein

This strong man I need not to talk to much, he is really a intrepid guy. Till now, we just know he own the legendary Rinnegan, but what is the ability of the legendary? He did not show his best, I really want to see more about him.

3rd—– Uchiha Madara

Yes, it is madara, his is very mysterious, not only his identity but also his ability. His could use his Ninjutsu to across his body and did not use any spiritism could go through the space, just this ability is not the common Ninja could do.

2nd— Zetsu

Talk about mysterious; Zetsu might be more than uchiha madara. To Zetsu, we just know he own dual personality, besides this, his ability is different from others, I do now know if you have notice, when Zetsu are tracking others, he always make his body appear in the trunk or ground, which is different from others. We could think that his Ninjutsu merged with the narure. He came from Grass ninja village, and the Ninjutsu we know about Grass Ninja is too little.

1st — Naruto Uzumaki

The first one is our protagonist Naruto Uzumaki, why could I say this? To Naruto, we must very familiar, besides Shadow Clone Technique, Rasengan, Great Ball, he also have the powerful Spiraling Shuriken. The 4 generations leave to Naruto are not only the Rasengan, but also more powerful strength. And what the strength that Uchiha Itachi leave to him, Naruto doesn’t know, we could not know either. So I think Naruto is first one who hidden his strength deepest.